DIAMOND BAR, Calif. -- Four members of a family were killed in a wrong-way freeway crash in California that also took the lives of two other people, including the sister of a woman arrested on suspicion of drunken driving and manslaughter, authorities said Monday.

Two people in a Ford Explorer - Gregorio Mejia-Martinez, 47, and Ester Delgado - died at the scene of Sunday's early morning crash on State Route 60, said Los Angeles County coroner's Lt. Fred Corral. Two other family members in the SUV - Leticia Ibarra, 42, and Jessica Jasmine Mejia, 20 - were declared dead at a hospital. All four were from Huntington Park.

Two additional victims were passengers in a Chevy Camaro that authorities said was driven by 21-year-old suspect, Olivia Culbreath of Fontana. Her sister, Maya Louise Culbreath, 24, of Rialto and Kristin Melissa Young, 24, of Chino were declared dead at the scene, Corral said.

Wendell Johnson of Rancho Cucamonga, a friend, told the San Gabriel Valley Tribune ( http://bit.ly/1egcAhY ) that Maya Culbreath recently had a baby and the group had been on a "girls' night out" in Fullerton.

"She just had a baby," Johnson said. "I was supposed to go see her."

Olivia Culbreath remained hospitalized in serious condition and was being treated for a broken femur and a ruptured bladder. She was arrested after being pulled from the badly mangled Camaro, CHP Officer Rodrigo Jimenez said.

Culbreath had a 2010 conviction for driving under the influence of alcohol stemming from a 2009 incident and her license was pulled but it was reinstated in 2011, according to Department of Motor Vehicle records.

Jimenez said the crash scene in Diamond Bar, a suburb east of Los Angeles, was horrific. Three people were ejected from their cars and the Camaro was barely recognizable.

Authorities said Culbreath was traveling north in the southbound lanes of State Route 57 before transitioning east in the westbound lanes where the Camaro collided head-on with the Ford Explorer. A Ford Freestyle then collided with the Explorer.

Witnesses told dispatchers the Camaro was speeding up to 100 mph, he said.

Evidence gathered at the scene included an alcoholic beverage, Jimenez told the Tribune.

The driver of the Ford Freestyle suffered minor injuries.

The investigation continued Monday. CHP Sgt. Carlo Fusco said he didn't know if Culbreath had a lawyer.